Dry matter yield and radiation use efficiency of four autumn sown top flowering annual clovers

Abstract

Monocultures of arrowleaf (Trifolium vesiculosum), balansa (T. michelianum), gland (T. glanduliferum) and Persian (T. resupinatum) clovers were sown on four dates in autumn and winter 2010. Dry matter (DM) accumulation was dependent on the duration of crop growth which was influenced by the time of sowing. Autumn sown crops which flowered latest had a longer duration of vegetative growth and consequently produced the highest dry matter yields. In the establishment year, autumn sown crops produced up to 17.5 t DM/ha for balansa, 12.5 t DM/ha for Persian, 11.0 t DM/ha for gland and 9.4 t DM/ha for arrowleaf at physiological maturity (P<0.05). Crops that were sown in winter produced the lowest yield, because reproductive development commenced earlier and therefore they matured earlier. 'Bolta' balansa clover had the highest radiation use efficiency of 2.1 g DM/MJ photosynthetically active radiation (PAR) absorbed followed by gland (1.6 g DM/MJ PAR), arrowleaf and Persian (1.3 g DM/MJ PAR) clovers. In the second year, regenerated dry matter production at full flower was up to 11.6 t/ha in balansa, 8.3 t/ha in Persian, 2.9 t/ha in gland but only 0.5 t/ha in arrowleaf clover (P<0.05). Thus, over the two years 'Bolta' balansa and 'Mihi' Persian clovers were the highest yielding and easiest to regenerate from seed in monocultures. 'Cefalu' arrowleaf failed to regenerate in the second year due to low population of seedling emergence. 'Prima' gland clover was low yielding because it flowered and matured without fully utilising the growing season. Keywords: biomass, canopy expansion, day length, light interception, thermal time.